package darwInvest.news.utility;

/*
 * 
   Porter stemmer in Java. The original paper is in

       Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,
       no. 3, pp 130-137,

   See also http://www.tartarus.org/~martin/PorterStemmer

   History:

   Release 1

   Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below.
   The words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1]
   is then out outside the bounds of b.

   Release 2

   Similarly,

   Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below.
   'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and
   b[j] is then outside the bounds of b.

   Release 3

   Considerably revised 4/9/00 in the light of many helpful suggestions
   from Brian Goetz of Quiotix Corporation (brian@quiotix.com).

   Release 4

 */

/**
 * Stemmer, implementing the Porter Stemming Algorithm
 *
 * The Stemmer class transforms a word into its root form.  The input
 * word can be provided a character at time (by calling add()), or at once
 * by calling one of the various stem(something) methods.
 * 
 * @author Martin Porter
 * @modified Kevin Dolan - for stylistic consistency with darwInvest
 */
public class Stemmer
{  
	private char[] b;
	private int i,     /* offset into b */
	i_end, /* offset to end of stemmed word */
	j, k;
	private static final int INC = 50;

	/* unit of size whereby b is increased */
	public Stemmer()
	{  
		b = new char[INC];
		i = 0;
		i_end = 0;
	}

	/**
	 * Add a character to the word being stemmed.  When you are finished
	 * adding characters, you can call stem(void) to stem the word.
	 */
	public void add(char ch)
	{  
		if (i == b.length) {  
			char[] new_b = new char[i+INC];
			for (int c = 0; c < i; c++) new_b[c] = b[c];
			b = new_b;
		}
		b[i++] = ch;
	}
	
	
	/** Adds wLen characters to the word being stemmed contained in a portion
	 * of a char[] array. This is like repeated calls of add(char ch), but
	 * faster.
	 */
	public void add(char[] w, int wLen)
	{  
		if (i+wLen >= b.length) {  
			char[] new_b = new char[i+wLen+INC];
			for (int c = 0; c < i; c++) 
				new_b[c] = b[c];
			b = new_b;
		}
		for (int c = 0; c < wLen; c++) 
			b[i++] = w[c];
	}
	
	/**
	 * After a word has been stemmed, it can be retrieved by toString(),
	 * or a reference to the internal buffer can be retrieved by getResultBuffer
	 * and getResultLength (which is generally more efficient.)
	 */
	public String toString() { 
		return new String(b,0,i_end); 
	}
	
	/**
	 * Returns the length of the word resulting from the stemming process.
	 */
	public int getResultLength() { 
		return i_end; 
	}
	
	/**
	 * Returns a reference to a character buffer containing the results of
	 * the stemming process.  You also need to consult getResultLength()
	 * to determine the length of the result.
	 */
	public char[] getResultBuffer() { 
		return b; 
	}
	
	/* cons(i) is true <=> b[i] is a consonant. */
	private final boolean cons(int i)
	{  
		switch (b[i]) {  
			case 'a': 
			case 'e':
			case 'i': 
			case 'o': 
			case 'u': 
				return false;
			case 'y': 
				return (i==0) ? true : !cons(i-1);
			default: return true;
		}
	}
	
	/* m() measures the number of consonant sequences between 0 and j. if c is
	      a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
	      presence,
	
	         <c><v>       gives 0
	         <c>vc<v>     gives 1
	         <c>vcvc<v>   gives 2
	         <c>vcvcvc<v> gives 3
	         ....
	 */
	private final int m() {  
		int n = 0;
		int i = 0;
		while(true) {  
			if (i > j) 
				return n;
			if (! cons(i)) 
				break; 
			i++;
		}
		i++;
		while(true) {  
			while(true) {  
				if (i > j) 
					return n;
				if (cons(i)) 
					break;
				i++;
			}
			i++;
			n++;
			while(true) {  
				if (i > j) 
					return n;
				if (! cons(i)) 
					break;
				i++;
			}
			i++;
		}
	}
	
	/* vowelinstem() is true <=> 0,...j contains a vowel */
	private final boolean vowelinstem() {  
		int i; 
		for (i = 0; i <= j; i++) 
			if (! cons(i)) 
				return true;
		return false;
	}
	
	/* doublec(j) is true <=> j,(j-1) contain a double consonant. */
	private final boolean doublec(int j) {  
		if (j < 1) 
			return false;
		if (b[j] != b[j-1]) 
			return false;
		return cons(j);
	}
	
	/* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
	      and also if the second c is not w,x or y. this is used when trying to
	      restore an e at the end of a short word. e.g.
	
	         cav(e), lov(e), hop(e), crim(e), but
	         snow, box, tray.
	
	 */
	private final boolean cvc(int i) {  
		if (i < 2 || !cons(i) || cons(i-1) || !cons(i-2)) 
			return false;
		int ch = b[i];
		if (ch == 'w' || ch == 'x' || ch == 'y') 
			return false;
		return true;
	}
	
	private final boolean ends(String s)
	{  
		int l = s.length();
		int o = k-l+1;
		if (o < 0) 
			return false;
		for (int i = 0; i < l; i++) 
			if (b[o+i] != s.charAt(i)) 
				return false;
		j = k-l;
		return true;
	}
	
	/* setto(s) sets (j+1),...k to the characters in the string s, readjusting
	      k. */
	
	private final void setto(String s) {  
		int l = s.length();
		int o = j+1;
		for (int i = 0; i < l; i++) 
			b[o+i] = s.charAt(i);
		k = j+l;
	}
	
	/* r(s) is used further down. */
	
	private final void r(String s) { 
		if(m() > 0)
			setto(s); 
	}
	
	/* step1() gets rid of plurals and -ed or -ing. e.g.
	
	          caresses  ->  caress
	          ponies    ->  poni
	          ties      ->  ti
	          caress    ->  caress
	          cats      ->  cat
	
	          feed      ->  feed
	          agreed    ->  agree
	          disabled  ->  disable
	
	          matting   ->  mat
	          mating    ->  mate
	          meeting   ->  meet
	          milling   ->  mill
	          messing   ->  mess
	
	          meetings  ->  meet
	
	 */
	private final void step1() {  
		if (b[k] == 's') {  
			if (ends("sses")) 
				k -= 2; 
			else if (ends("ies")) 
				setto("i"); 
			else if (b[k-1] != 's')
				k--;
		}
		if (ends("eed")) { 
			if (m() > 0) 
				k--; 
		} 
		else if ((ends("ed") || ends("ing")) && vowelinstem()) {  
			k = j;
			if (ends("at")) 
				setto("ate"); 
			else if (ends("bl")) 
				setto("ble"); 
			else if (ends("iz")) 
				setto("ize");
			else if (doublec(k)) {  
				k--;
				int ch = b[k];
				if (ch == 'l' || ch == 's' || ch == 'z')
					k++;
			}
			else if (m() == 1 && cvc(k))
				setto("e");
		}
	}
	
	/* step2() turns terminal y to i when there is another vowel in the stem. */
	
	private final void step2() {
		if (ends("y") && vowelinstem()) 
			b[k] = 'i'; 
	}
	
	/* step3() maps double suffices to single ones. so -ization ( = -ize plus
	      -ation) maps to -ize etc. note that the string before the suffix must give
	      m() > 0. */
	
	private final void step3() { 
		if (k == 0) return; /* For Bug 1 */ 
		switch (b[k-1])
		{
			case 'a':
				if (ends("ational")) { 
					r("ate"); 
					break; 
				}
				if (ends("tional")) { 
					r("tion"); 
					break; 
				}
				break;
			case 'c':
				if (ends("enci")) {
					r("ence"); 
					break; 
				}
				if (ends("anci")) { 
					r("ance");
					break; 
				}
				break;
			case 'e':
				if (ends("izer")) { 
					r("ize"); 
					break; 
				}
				break;
			case 'l':
				if (ends("bli")) { 
					r("ble"); 
					break; 
				}
				if (ends("alli")) {
					r("al"); 
					break; 
				}
				if (ends("entli")) {
					r("ent"); 
					break; 
				}
				if (ends("eli")) { 
					r("e"); 
					break; 
				}
				if (ends("ousli")) { 
					r("ous"); 
					break; 
				}
				break;
			case 'o': 
				if (ends("ization")) {
					r("ize"); 
					break; 
				}
				if (ends("ation")) {
					r("ate"); 
					break; 
				}
				if (ends("ator")) {
					r("ate"); 
					break; 
				}
				break;
			case 's': 
				if (ends("alism")) { 
					r("al"); 
					break; 
				}
				if (ends("iveness")) { 
					r("ive"); 
					break; 
				}
				if (ends("fulness")) { 
					r("ful"); 
					break; 
				}
				if (ends("ousness")) { 
					r("ous"); 
					break; 
				}
				break;
			case 't': 
				if (ends("aliti")) {
					r("al"); 
					break; 
				}
				if (ends("iviti")) { 
					r("ive"); 
					break; 
				}
				if (ends("biliti")) { 
					r("ble"); 
					break; 
				}
				break;
			case 'g': 
				if (ends("logi")) { 
					r("log"); 
					break; 
				}
		} 
	}
	
	/* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */
	private final void step4() { 
		switch (b[k]) {
			case 'e':
				if (ends("icate")) { 
					r("ic"); 
					break; 
				}
				if (ends("ative")) { 
					r(""); 
					break; 
				}
				if (ends("alize")) { 
					r("al"); 
					break; 
				}
				break;
			case 'i': 
				if (ends("iciti")) { 
					r("ic"); 
					break; 
				}
				break;
			case 'l': 
				if (ends("ical")) { 
					r("ic"); 
					break; 
				}
				if (ends("ful")) { 
					r(""); 
					break; 
				}
				break;
			case 's': 
				if (ends("ness")) { 
					r(""); 
					break; 
				}
				break;
		} 
	}
	
	/* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */
	
	private final void step5() {   
		if (k == 0) 
			return; /* for Bug 1 */ 
		switch (b[k-1]) {  
			case 'a': 
				if (ends("al")) 
					break; 
				return;
			case 'c': 
				if (ends("ance")) 
					break;
				if (ends("ence")) 
					break; 
				return;
			case 'e': 
				if (ends("er")) 
					break; 
				return;
			case 'i': 
				if (ends("ic")) 
					break; 
				return;
			case 'l': 
				if (ends("able")) 
					break;
				if (ends("ible")) 
					break; 
				return;
			case 'n': 
				if (ends("ant")) 
					break;
				if (ends("ement")) 
					break;
				if (ends("ment")) 
					break;
				/* element etc. not stripped before the m */
				if (ends("ent")) 
					break; 
				return;
			case 'o': 
				if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't')) 
					break;
				/* j >= 0 fixes Bug 2 */
				if (ends("ou")) 
					break; 
				return;
				/* takes care of -ous */
			case 's': 
				if (ends("ism")) 
					break; 
				return;
			case 't': 
				if (ends("ate")) 
					break;
				if (ends("iti")) 
					break; 
				return;
			case 'u': 
				if (ends("ous")) 
					break; 
				return;
			case 'v': 
				if (ends("ive")) 
					break; 
				return;
			case 'z': 
				if (ends("ize")) 
					break; 
				return;
			default: return;
		}
		if (m() > 1) 
			k = j;
	}
	
	/* step6() removes a final -e if m() > 1. */
	private final void step6() {  
		j = k;
		if (b[k] == 'e') {  
			int a = m();
			if (a > 1 || a == 1 && !cvc(k-1)) 
				k--;
		}
		if (b[k] == 'l' && doublec(k) && m() > 1) 
			k--;
	}
	
	/** Stem the word placed into the Stemmer buffer through calls to add().
	 * Returns true if the stemming process resulted in a word different
	 * from the input.  You can retrieve the result with
	 * getResultLength()/getResultBuffer() or toString().
	 */
	public void stem() {  
		k = i - 1;
		if (k > 1) { 
			step1(); 
			step2(); 
			step3(); 
			step4(); 
			step5(); 
			step6(); 
		}
		i_end = k+1; 
		i = 0;
	}
}
